Lymphocyte stimulation by allogeneic tissue cells in rats: with special reference to differential survival of skin and kidney allografts.

The ability of isolated skin and kidney cells to activate allogeneic lymphocytes in vitro was studied in the MHC-identical and incompatible rat strains. The preparation of these cells and optimal culture conditions were summarized. 3H-thymidine uptake was strongest with skin epidermal cells and weakest with kidney cells. The results obtained from fractionated cells indicated that both Langerhans (Ia positive) and other cells (Ia negative) of the skin epidermis stimulated lymphocytes equally well and that only glomerulus and whole kidney cells stimulated, whereas cells fom the medulla and cultured epithelium failed to do so. It was suggested that skin epidermal cells possess lymphocyte-activating antigens other than Ia antigens that may be responsible for MHC-identical graft rejection. The weaker reaction by kidney cells and the limited localization of lymphocyte-activating determinants suggest that kidney cells may not express specific alloantigens detectable by the procedure employed; these cells obviously carry only a limited amount of Ia antigens.